The present invention relates to air conditioner systems for automotive vehicles, and more particularly to such an air conditioner system including an auxiliary heater.
There are known various air conditioner systems which generally include a heater core disposed in an air flow duct for heating air flowing therethrough to a vehicle passenger compartment. The air while passing through the heater core is subjected to a heat-exchange relationship with engine cooling water which is circulating through the heater core to give up heat to the air. A drawback of such known air conditioner systems lies in the difficulty of producing a sufficient heating effect while the engine and accordingly the engine cooling water is cold, particularly when the engine is started from a cold condition. It has therefore been long desired to devise an air conditioner system capable of supplying hot air soon after the engine is started from a cold condition.
As disclosed in Japanese Utility Model Laid-Open Publication No. (JP-A) 57-127116, an improved air conditioner system includes a combustion heater for heating engine cooling water before it is circulated through a heater core. This air conditioner system is still disadvantageous in that the engine cooling water has a relatively large specific heat, requiring a considerable period of time to be heated to an elevated temperature high enough to cause a rapid increase in the temperature of air passing through the heater core.